1. Field of the Invention
The present invention relates to a coaxial coarse and fine adjusting device having a plurality of handles in a coaxial fashion, and more particularly, to a coaxial coarse and fine adjusting device suitable for use as a focusing device for a microscope.
2. Related Background Art
A conventional focusing device for a microscope includes a two-step moving mechanism which consists of a fine adjusting mechanism used to finely focus an intermediate or high magnification objective, and a coarse adjusting mechanism used to finely focus a low magnification objective, to coarsely focus a low, intermediate or high magnification objective, and to move up or down through a large distance a stage for the exchange of a sample or for oil immersion operation.
The focusing fine and coarse adjusting device of the above-described type which includes the two-step moving mechanism has one linear movement guiding mechanism with the moving mechanism which employs coaxial fine and coarse adjustment handles attached thereto, as shown in FIG. 5. The structure thereof will be described in detail below.
In the device shown in FIG. 5, a linear movement guiding inner race 101 is mounted on a movable stage (not shown) on which a sample is placed, and a rack 102 is fixed to the lower portion of the linear movement guiding inner race 101. An outer race 103a as viewed on the left in FIG. 5 is fixed to a microscope body 104, and an outer race 103b as viewed on the right in FIG. 5 is formed integrally with the microscope body 104. The outer races 103a and 103b support the inner race 101 through a large number of balls (including balls 105a and 105b shown in FIG. 5) arranged in a direction perpendicular to the surface of the paper in such a manner that the outer race 101 can be moved in a direction perpendicular to the paper.
A hollow fixed cylinder 106 for a bearing is fitted in a through-hole 104a formed in the microscope body 104. The hollow fixed cylinder 106 is fixed to the microscope body 104 by means of fixing screws 107 and 108. A hollow cylindrical rotation transmission shaft 109 is rotatably fitted in the left part of a hollow portion of the fixed cylinder 106 for the bearing. The rotation transmission shaft 109 has a pinion 109a formed on a peripheral surface thereof. The pinion 109a is in mesh with the rack 102 which passes through an elongated hole 106a formed in the circumferential direction of the fixed cylinder 106. A gear 109b is provided on one end of the rotation transmission shaft 109 which is located at the left end of the fixed cylinder 106. A hollow cylindrical coarse adjustment coupling shaft 110 is rotatably fitted in the right part of the hollow portion of the fixed cylinder 106 and a hollow portion of the rotation transmission shaft 109. A first coarse adjusting handle 110a is fixed to the left end of the coarse adjustment coupling shaft 110 and a second coarse adjusting handle 110b is fixed to the right end of the coarse adjustment coupling shaft 110. A rod-like fine adjustment coupling shaft 111 is rotatably fitted in a hollow portion of the coarse adjustment coupling shaft 110. A first fine adjusting handle 111a is fixed to the left end of the fine adjustment coupling shaft 111 and a second fine adjusting handle 111b is fixed to the right end of the fine adjustment coupling shaft 111.
In an inner hollow portion 110c of the coarse adjusting handle 110a which is closed by the first fine adjusting handle 111a, a small gear 111c is fixed to the portion of the fine adjustment coupling shaft 111 which is located in that inner hollow portion. The small gear 111c is in mesh with a large gear 112a which is integrally formed with a small gear 112b. The large gear 112a and the small gear 112b are used as a stepped gear 112. The small gear 112b is inserted in a circular hole 110d formed in a side wall portion of the coarse adjusting handle 110a. The gears 112a and 112b are rotatably supported on a plate-like ring 113a fixed to the side wall portion of the coarse adjusting handle 110a by a fixing screw 113b. Part of the inner peripheral surface of the circular hole 110d is notched to form an opening, and the small gear 112b is in mesh with the gear 109b through this opening.
Between a ring member 114 threadedly engaged with an externally threaded portion 106b formed on one end of the fixed cylinder 106 and the coarse adjusting handle 110a there is provided a conical plate spring 115a. Also, a conical plate spring 115b is held between the fine adjusting handle 111b and the coarse adjusting handle 110b which are located on the right as viewed in FIG. 5. The frictional force of the plate spring 115a located on the left is adjusted to a value larger than or equal to that of the plate spring 115b located on the right by the rotation of the ring member 114. A sliding member 116 is held between the coarse adjusting handle 110b and the other end of the fixed cylinder 106.
The coarse and fine adjustment operation conducted by the thus-arranged coarse and fine adjusting device having coaxial handles will be described below.
The fine adjusting device is operated by the rotation of at least one of the fine adjusting handles 111a and 111b. When the frictional force of the plate spring 115a located on the left as viewed in FIG. 5 is larger than that of the plate spring 115b located on the right, even if the fine adjusting handle 111a or 111b is rotated, the coarse adjusting handles 110a and 110b and the coarse adjustment coupling shaft 110 remain stationary due to the frictional force of the plate spring 115a. Thus, rotation of the fine adjusting handle 111a or 111b rotates the coupling shaft 111 in a state in which it is supported by the coarse adjustment coupling shaft 110 which is in a fixed state. Also, when the frictional force of the right and left plate springs 115a and 115b is equal, even if the fine adjusting handle 111a or 111b is rotated, the coarse adjusting handles 110a and 110b and the coarse adjustment coupling shaft 110 remain unrotated due to the frictional force between the fixed cylinder 106 and the coarse adjusting coupling shaft 110, and the fine adjustment coupling shaft 111 thus rotates in a state in which it is supported by the coarse adjustment coupling shaft 110 which is in a fixed state, as in the above case. As the fine adjustment coupling shaft 111 is rotated by the rotation of the fine handle 111a or 111b, the small gear 111c rotates together with the fine adjustment coupling shaft 111, thereby rotating the large gear 112a in a reduced speed with respect to the coarse adjusting handle 110a which is in a fixed state. In consequence, the gear 109b also rotates in a reduced speed by the rotation of the small gear 112b which is formed integrally with the large gear 112a, thereby rotating the rotation transmission shaft 109 in the same direction in which the fine adjusting handle 111a or 111b is rotated. As the rotation transmission shaft 109 rotates, the pinion 109a also rotates, thereby moving the rack 102 which is in mesh with the pinion 109a in a direction perpendicular to the surface of the paper. Movement of the rack 102 moves the outer race 101 and the movable stage (not shown) in the same direction.
The coarse adjusting device is operated by the rotation of at least one of the coarse adjusting handles 110a and 110b against the frictional force of the left plate spring 115a. As the right coarse adjusting handle 110b is rotated, the fine adjusting handle 111b, the fine adjustment coupling shaft 111 and the left fine adjusting handle 111a rotate due to the frictional force of the plate spring 115b, thereby rotating the small gear 111c. However, since the left coarse adjusting handle 110a also rotates at that time, the large gear 112a is not rotated about it own axis but rotates about the fine adjustment coupling shaft 111 by the rotation of the small gear 111c in a state in which it is in mesh with the small gear 111c. Consequently, the small gear 112b which is formed integrally with the large gear 112a also rotates about the shaft 111 in the same direction, thereby rotating the rotation transmission shaft 109 through the gear 109b which is in mesh with the small gear 112b in the same direction in which the coarse adjusting handle 110a or 110b is rotated. Rotation of the rotation transmission shaft 109 moves, through the pinion 109a and the rack 102, the outer race 101 in a direction perpendicular to the surface of the paper, which in turn moves the movable stage (not shown) in the same direction as that in which the outer race 101 is moved.
When the conventional coaxial fine and coarse adjusting device, including the fine adjusting mechanism and the coarse adjusting mechanism, is used for observation of samples or for various experiments conducted on the samples, it is used together with various attachments such as X-Y stage or other devices. Such attachments or devices are placed close to and around the microscope body 104. However, the handles 110a, 110b, 111a and 111b protruding from the microscope body 104, as shown in FIG. 5, make it difficult for various attachments to be placed around the microscope body 104. This inconvenience may be eliminated by removing at least one of the fine and coarse adjusting handles. However, removal of the handles leads to the following problems.
When the coarse adjusting handle 110a is to be removed after the fine adjusting handle 111a is removed from the fine adjustment coupling shaft 111 by loosening the screw 111d, since the stepped gear 112 is rotatably supported on the coarse adjusting handle 110a through the plate-shaped ring 113a which is fixed to the coarse adjusting handle 111a by the fixing screw 113b, the plate-shaped ring 113a and the stepped gear 112 must be removed by removing the fixing screw 113b. Then, the coarse adjusting handle 110a must be removed from the coarse adjustment coupling shaft 110. This is a troublesome task. Furthermore, removal of the stepped gear 112 eliminates engagement of the small gear 112b with the gear 109b of the rotation transmission shaft 109. This makes transmission of rotation to the rotation transmission shaft 109 impossible and, hence, defeats the function of this fine and coarse adjusting device.
When the coarse adjusting handle 110b is to be removed from the coarse adjustment coupling shaft 110 after the fine adjusting handle 111b is removed from the fine adjustment coupling shaft 111 by loosening the screw 111e, the plate spring 115b must also be removed. Removal of the handles 110b and 111b is therefore also a troublesome task. Moreover, removal of the plate spring 115b leaves an inadequate frictional force between the coarse adjustment coupling shaft 110 and the fine adjustment coupling shaft 111. This makes concurrent rotation of the handles 110a and 111a required for the coarse adjusting operation impossible, and thus defeats the function of the fine and coarse adjusting device.
When the fine adjusting handle 111a is mounted subsequent to the mounting of the coarse adjusting handle 110a, the following time-consuming tasks are necessary: the small gear 112b of the stepped gear 112 is first inserted into the circular hole 110d in the side wall of the coarse adjusting handle 110a and then engaged with the gear 109b of the rotation transmission shaft 109. Next, the stepped gear 112 is made to be rotatably supported by the plate-shaped ring 113a and then fixed by the fixing screw 113b. On the other hand, mounting of the coarse adjusting handle 110b and the fine adjusting handle 111b requires insertion of the plate spring 115b and adjustment of the urging force thereof. This is also a time-consuming task.